Abstract
Abstract In informal landfills, leachate leaked into the underlying soil and groundwater has been gaining increasing attention. Recently, an informal low-permeability landfill site in northern China was investigated in detail, and it was found that the groundwater was contaminated by leachate. A groundwater flow and contamination transport model was developed using FEFLOW to forecast contaminant transport and evaluate feasible pollutant control schemes. In this model, good matches between the simulated and observed groundwater level and good matches between the simulated and observed concentration of ammonia nitrogen show that the established model can reproduce the process of groundwater movement effectively. Three kinds of schemes, including natural conditions, pollution source removal, and pump and treatment, were simulated, and the results were compared. The results showed that, under natural conditions, the pollution does not travel far horizontally and vertically. Removal of pollution sources has little effect on the concentration of ammonia nitrogen in groundwater over a period of 100 years. The pump and treatment system can effectively remove high concentrations of ammonia nitrogen in the groundwater of the landfill site, with a maximum decline of over 90%. Therefore, the pump and treatment method may be valid for short-term soil and groundwater remediation.
Highlights
Landfills are a major waste disposal option worldwide
The objective of this study is to evaluate the effect of groundwater pollution control methods in this low-permeability landfill site
The Jing-Jin-Ji region of China with an informal low-permeability landfill site was studied in detail
Summary
Landfills are a major waste disposal option worldwide. Formal landfills must meet strict design, operation, and closure requirements, and leachate from the landfill must be collected and treated appropriately to prevent landfill leachate from contaminating the surrounding soil and groundwater (Mukherjee et al 2015). Informal landfills are not constructed and operated in line with applicable standards and have the characteristics of simple construction and lack of environmental protection measures (Wan et al 2021). Many informal landfills still exist especially in developing countries (Hong et al 2018). Researchers have identified approximately 200 hazardous compounds, such as aromatic, halogenated, ammonium, and sulfur compounds and heavy metals, in various landfill leachates (Jensen et al 1999; Lou et al 2009; Gajski et al 2012). Pollutants in landfill leachate have cumulative and harmful effects on the ecology and food chain, leading to several health issues, including carcinogenic effects, acute toxicity, and genetic toxicity in humans (Kjeldsen et al 2002). Groundwater pollution induced by leachate leaks from informal landfills is becoming an environmental issue globally (Han et al 2016)
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